Circuit for driving gate of power mosfet

ABSTRACT

A circuit for driving a gate of a power metal-oxide semiconductor field effect transistor (MOSFET), which uses a higher voltage than a gate controller is provided. The circuit is able to safely and effectively transmits an output signal of a gate controller irrespective of a frequency and a duty-cycle of the output signal when transmitting the output signal of the gate controller to the power MOSFET using a higher voltage than the gate controller. Accordingly, the circuit is suitable for a case where the duty-cycle of the output signal of the gate controller dramatically changes and the frequency is irregular.

FIELD OF THE INVENTION

The present invention relates to a circuit for driving a gate of a powermetal-oxide semiconductor field effect transistor (MOSFET) in a digitalaudio amplifier, and more particularly, to a circuit for driving a gateof a power MOSFET using a higher voltage than a gate controller whichcontrols the gate of the power MOSFET.

BACKGROUND OF THE INVENTION

FIG. 1 is a drawing illustrating a conventional circuit for driving agate of a power metal-oxide semiconductor field effect transistor(MOSFET) in a digital audio amplifier. Referring to FIG. 1, a firstpower source voltage V_(DD), that is, a positive power source voltage,is applied to a source of a power PMOSFET transistor PM and a secondpower source voltage V_(SS), that is, a negative power source voltage,is applied to a source of a power NMOSFET transistor NM. A gatecontroller 11 uses a third power source voltage V_(CC), which is lowerthan the first power source voltage V_(DD), and a fourth power sourcevoltage V_(EE), which is lower than the second power source voltageV_(SS).

In a conventional circuit for driving a gate 13, capacitors C₁ and C₂are generally used to maintain a voltage difference between the gatecontroller 11 and the power MOSFET transistors PM and NM, and totransmit an output signal of the gate controller 11 to the power MOSFETtransistors PM and NM. In addition, resistances R_(1 and R) ₂ arefurther included to charge and discharge the capacitors C₁ and C₂.

FIGS. 2A through 2C illustrate voltages of main nodes V_(GC), V_(GP),and V_(GN) of the circuit of FIG. 1 when a duty-cycle is very small.

The conventional circuit for driving the gate 13 does not have a problemin operating when the duty-cycle of the output signal V_(GC) of the gatecontroller 11 is in a range of about 50%. However, when the duty-cycleof the output signal V_(GC) of the gate controller 11 is beyond 50%, anon resistance is decreased in one of the power MOSFET transistors PM andNM, while the on resistance is increased in the other of the powerMOSFET transistors PM and NM. That is, as shown in FIG. 2B, an amplitudeof a gate signal V_(GP) of the power PMOSFET transistor PM is equal toan amplitude of the output signal V_(GC) of the gate controller 11, thatis, V_(CC)-V_(EE). However, the gate signal V_(GP) goes only a littledown from a source potential V_(DD), drops slightly and thus, aneffective gate voltage, which may turn the power PMOSFET transistor PMon, becomes small. Therefore, the power PMOSFET transistor PM is notturned on, or even if it is turned on, the power PMOSFET transistor PMhas large resistance.

On the contrary, when the duty-cycle is very large, the power NMOSFETtransistor NM is not turned on, or even if it is turned on, the powerNMOSFET transistor NM has large resistance. That is, operation of theconventional circuit for driving the gate depends on the frequency andduty-cycle of the output signal of the gate controller 11, and when theduty-cycle is very small or large, the power MOSFET transistors cannotsafely nor effectively operate.

SUMMARY OF THE INVENTION

To solve the above and other problems, the present invention provides acircuit for driving a gate, which safely and effectively drives powerMOSFET transistors irrespective of a frequency and duty-cycle of a gatecontroller, especially when the power MOSFET transistors use a highervoltage than the gate controller.

According to an aspect of the present invention, there is provided

-   a circuit for driving a gate of a power MOSFET in a digital audio    amplifier, which includes a power PMOSFET transistor in which a    first power source voltage is applied to a source and an output    terminal is connected to a drain; a power NMOSFET transistor in    which the output terminal is connected to a drain and a second power    source voltage is applied to a source; a gate controller which uses    a third power source voltage which is lower than the first power    source voltage and a fourth power source voltage which is lower than    the second power source voltage, and controls gates of the power    PMOSFET and NMOSFET transistors; and an output filter which is    connected to the output terminal and has an inductor and a    capacitor, the circuit comprising: a first resistance connected    between the first power source voltage and the gate of the power    PMOSFET transistor; a second resistance connected between the second    power source voltage and the gate of the power NMOSFET transistor; a    first capacitor connected between an output terminal of the gate    controller and the gate of the power PMOSFET transistor; a second    capacitor connected between the output terminal of the gate    controller and the gate of the power NMOSFET transistor; a first    diode connected between the output terminal of the gate controller    and the gate of the power PMOSFET transistor; and a second diode    connected between the output terminal of the gate controller and the    gate of the power NMOSFET transistor.

According to another aspect of the present invention, there is provideda circuit for driving a gate of a power MOSFET in a digital audioamplifier, which includes a power PMOSFET transistor in which a firstpower source voltage is applied to a source and an output terminal isconnected to a drain; a power NMOSFET transistor in which the outputterminal is connected to a drain and a second power source voltage isapplied to a source; a gate controller which use a third power sourcevoltage lower than the first power source voltage and a fourth powersource voltage lower than the second power source voltage, and controlsgates of the power PMOSFET and NMOSFET transistors; and an output filterwhich is connected to the output terminal and has an inductor and acapacitor, the circuit comprising: a first resistance connected betweenthe first power source voltage and the gate of the power PMOSFETtransistor; a second resistance connected between the second powersource voltage and the gate of the power NMOSFET transistor; a firstcapacitor connected between the output terminal of the gate controllerand the gate of the power PMOSFET transistor; a second capacitorconnected between the output terminal of the gate controller and thegate of the power NMOSFET transistor; a first diode, one end of which isconnected to the first power source voltage; a second diode, one end ofwhich is connected to the other end of the first diode and other end ofwhich is connected to the gate of the power PMOSFET transistor; a thirddiode, one end of which is connected to the second power source voltageand other end of which is connected to the gate of the power PMOSFETtransistor; and a fourth diode, one end of which is connected to otherend of the third diode and other end of which is connected to the gateof the power NMOSFET transistor.

According to still another aspect of the present invention, there isprovided a circuit for driving a gate of a power MOSFET in a digitalaudio amplifier, which includes a power PMOSFET transistor in which afirst power source voltage is applied to a source and an output terminalis connected to a drain; a power NMOSFET transistor in which the outputterminal is connected to a drain and a second power source voltage isapplied to a source; a gate controller which use a third power sourcevoltage which is lower than the first power source voltage and a fourthpower source voltage which is lower than the second power sourcevoltage, and controls gates of the power PMOSFET and NMOSFETtransistors; and an output filter which is connected to the outputterminal and has an inductor and a capacitor, the circuit comprising: afirst resistance connected between the first power source voltage andthe gate of the power PMOSFET transistor; a second resistance connectedbetween the second power source voltage and the gate of the powerNMOSFET transistor; a first capacitor, one end of which is connected theoutput terminal of the gate controller; a second capacitor, one end ofwhich is connected to the output terminal of the gate controller; afirst diode, one end of which is connected to the first power sourcevoltage and other end of which is connected to the gate of the powerPMOSFET transistor; a second diode, one end of which is connected toother end of the first capacitor and other end of which is connected tothe gate of the power PMOSFET transistor; a third diode, one end ofwhich is connected to the second power source voltage and other end ofwhich is connected to the gate of the power NMOSFET transistor; and afourth diode, one end of which is connected to other end of the secondcapacitor and other end of which is connected to the gate of the powerNMOSFET transistor.

The circuit for driving the gate according to the another or stillanother aspect of the present invention may further comprise a currentsource which is connected to the gates of the power PMOSFET and NMOSFETtransistors and the output terminal of the gate controller.

Accordingly, the circuit for driving the gate according to presentinvention has an advantage in that the circuit safely and effectivelytransmits the output signal of the gate controller irrespective of thefrequency and duty-cycle of the output signal when transmitting theoutput signal of the gate controller to the power MOSFET transistorusing a higher power source voltage than the gate controller.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a drawing illustrating a conventional circuit for driving agate of a power metal-oxide semiconductor field effect transistor(MOSFET) in a digital audio amplifier;

FIGS. 2A through 2C illustrate voltages of main nodes V_(GC), V_(GP),and V_(GN) of the circuit of FIG. 1 when a duty-cycle is very small;

FIG. 3 is a drawing illustrating a circuit for driving a gate of a powerMOSFET in a digital audio amplifier, according to a first embodiment ofthe present invention;

FIG. 4 is a drawing illustrating a circuit for driving a gate of a powerMOSFET in a digital audio amplifier, according to a second embodiment ofthe present invention;

FIG. 5 is a drawing illustrating a circuit for driving a gate of a powerMOSFET in a digital audio amplifier, according to a third embodiment ofthe present invention;

FIG. 6 is a drawing illustrating a circuit for driving a gate of a powerMOSFET in a digital audio amplifier, according to a fourth embodiment ofthe present invention; and

FIG. 7 is a drawing illustrating a circuit for driving a gate of a powerMOSFET in a digital audio amplifier, according to a fifth embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully with reference toaccompanying drawings in which exemplary embodiments of the presentinvention are shown. To facilitate understanding, identical referencenumerals have been used, where possible, to designate identical elementsthat are common to the figures.

FIG. 3 is a drawing illustrating a circuit for driving a gate of a powerMOSFET in a digital audio amplifier, according to a first embodiment ofthe present invention.

Referring to FIG. 3, a first power source voltage V_(DD), that is, apositive power source voltage, is applied to a source of a power PMOSFETtransistor PM₁ and a second power source voltage V_(SS), that is, anegative power source voltage, is applied to a source of a power NMOSFETtransistor NM₁. A gate controller 31 uses a third power source voltageV_(CC), which is lower than the first power source voltage V_(DD) and afourth power source voltage V_(EE), which is lower than the second powersource voltage V_(SS). A filter 35, which is formed of an inductor L anda capacitor C, is connected to an output terminal V_(D), that is, aconnecting point between the power PMOSFET transistor PM₁ and the powerNMOSFET transistor NM₁, and an output terminal V_(OUT) of the filter 35is connected to a speaker 37.

A circuit for driving a gate 33 comprises a first resistance R₁, whichis connected between the first power source voltage V_(DD) and a gate ofthe power PMOSFET transistor PM₁, a second resistance R₂, which isconnected between the second power source voltage V_(SS) and a gate ofthe power NMOSFET transistor NM₁, a first capacitor C₁, which isconnected between an output terminal of a gate controller 31 and thegate of the power PMOSFET transistor PM₁, a second capacitor C₂, whichis connected between the output terminal of the gate controller 31 andthe gate of the power NMOSFET transistor NM₁, a first diode D₁, which isconnected between the output terminal of the gate controller 31 and thegate of the power PMOSFET transistor PM₁, and a second diode D₂, whichis connected between the output terminal of the gate controller 31 andthe gate of the power NMOSFET transistor NM₁.

The first and second diodes D₁ and D₂ may be general diodes, but theyare preferably zener diodes.

Specifically, the diodes D₁ and D₂ are connected to the capacitorsC_(1 and C) ₂ in parallel in order to prevent the capacitors C₁ and C₂from being overcharged. Typically, while the capacitors C₁ and C₂compensate for voltage differences between the gate controller 31 andthe power MOSFET transistors PM₁ and NM₁, the capacitors C_(1 and C) ₂transmit a signal component intact. Therefore, a voltage correspondingto a difference between the first power source voltage V_(DD) and thethird power source voltage V_(CC) is charged in the capacitor C₁, whichis connected between the gate controller 31 and the power PMOSFETtransistor PM₁, and a voltage corresponding to a difference between thesecond power source voltage V_(SS) and the fourth power source voltageV_(EE) is charged in the capacitor C₂, which is connected between thegate controller 31 and the power NMOSFET transistor NM₁.

In the circuit of FIG. 3, a desired voltage can be charged in thecapacitors C_(1 and C) ₂ by adjusting a breakdown voltage of the zenerdiodes D₁ and D₂. Moreover, unlike the conventional circuit of FIG. 1,the capacitors C₁ and C₂ are charged and discharged only through theresistances R₁ and R₂ in the circuit of FIG. 3, and thus, the circuit isable to sufficiently reduce an operating current and safely operateirrespective of a duty-cycle by increasing values of the resistances R₁and R₂.

FIG. 4 is a drawing illustrating a circuit for driving a gate of a powerMOSFET in a digital audio amplifier, according to a second embodiment ofthe present invention.

Referring to FIG. 4, a circuit for driving a gate 43 comprises a firstresistance R₁, which is connected between a first power source voltageV_(DD) and a gate of a power PMOSFET transistor PM₁, a second resistanceR₂, which is connected between a second power source voltage V_(SS) anda gate of the power NMOSFET transistor NM₁, a first capacitor C₁, whichis connected between an output terminal of a gate controller 31 and thegate of the power PMOSFET transistor PM₁, a second capacitor C₂, whichis connected between the output terminal of the gate controller 31 andthe gate of the power NMOSFET transistor NM₁, a first diode D₁, one endof which is connected to the first power source voltage V_(DD), a seconddiode D₂, one end of which is connected to the other end of the firstdiode D₁ and other end of which is connected to the gate of the powerPMOSFET transistor PM₁, a third diode D₃, one end of which is connectedto the second power source voltage V_(SS), and a fourth diode D₄, oneend of which is connected to other end of the third diode D₃ and otherend of which is connected to the gate of the power NMOSFET transistorNM₁.

The first through fourth diodes D₁, D₂, D₃, and D₄ may be generaldiodes, but they are preferably zener diodes.

As illustrated in FIG. 4, although the power source voltages V_(DD) andV_(SS) which are applied to the power MOSFET transistors PM₁ and NM₁ arechanged, the circuit for driving the gate 43 constantly maintainsgate-source voltages of the power MOSFET transistors PM₁ and NM₁ byzener diodes D₁ and D₃. However, when the power MOSFET transistors PM₁and NM₁ are turned off, another diodes D₂ and D₄ are used in order toprevent the capacitors C₁ and C₂ to be discharged through the zenerdiodes D₁ and D₃. In this case, general diodes may be used, but whenzener diodes are used, there is an advantage in limiting the gate-sourcevoltages of the power MOSFET transistors PM₁ and NM₁. In addition, atrade-off between voltages applied to the power MOSFET transistors PM₁and NM₁ and currents charged and discharged in the capacitors C₁ and C₂is possible by adjusting a breakdown voltage of the diodes D₂ and D₄.

FIG. 5 is a drawing illustrating a circuit for driving a gate of a powerMOSFET in a digital audio amplifier, according to a third embodiment ofthe present invention.

Referring to FIG. 5, a circuit for driving a gate 53 comprises a firstresistance R₁, which is connected between a first power source voltageV_(DD) and a gate of a power PMOSFET transistor PM₁, a second resistanceR₂, which is connected between a second power source voltage V_(SS) anda gate of a power NMOSFET transistor NM₁, a first capacitor C₁, one endof which is connected to an output terminal of a gate controller 31, asecond capacitor C₂, one end of which is connected to the outputterminal of the gate controller 31, a first diode D₁, one of which isconnected to the first power source voltage V_(DD) and other end ofwhich is connected to the gate of the power PMOSFET transistor PM₁, asecond diode D₂, one end of which is connected to the other end of thefirst capacitor C₁ and other end of which is connected to the gate ofthe power PMOSFET transistor PM₁, a third diode D₃, one end of which isconnected to the second power source voltage V_(SS) and other end ofwhich is connected to the gate of the power NMOSFET transistor NM₁, anda fourth diode D₄, one end of which is connected to the other end of thesecond capacitor C₂, and other end of which is connected to the gate ofthe power NMOSFET transistor NM₁.

The first through fourth diodes D₁, D₂, D₃, and D₄ may be generaldiodes, but they are preferably zener diodes.

More particularly, when the power MOSFET transistors PM₁ and NM₁ areturned off, the circuit for driving the gate 53 prevents a gate voltagefrom going beyond a scope of the power source voltages V_(DD) and V_(SS)by connecting the zener diodes D₂ and D₄, which prevent the chargedcapacitors C_(1 and C) ₂ from being discharged, to the capacitorsC_(1 and C) ₂ in series. Therefore, an overvoltage is not applied to thepower MOSFET transistors PM₁ and NM₁.

Meanwhile, a breakdown occurs in a turned-off power MOSFET transistoramong the power MOSFET transistors PM₁ and NM₁ _(—) when adjusting thebreakdown voltage of the zener diodes D₂ and D₄, which block thedischarge of the capacitors C₁ and C₂.

Resistances R_(1 and R) ₂ of FIGS. 4 and 5 are not essential elements ina switching operation and play a supplementary role of turning the powerMOSFET transistors PM₁ and NM₁ off by charging the capacitors C₁ and C₂when the gate controller 31 does not operate.

FIG. 6 is a drawing illustrating a circuit for driving a gate of a powerMOSFET in a digital audio amplifier, according to a fourth embodiment ofthe present invention.

Referring to FIG. 6, a circuit for driving a gate 63 further comprises acurrent source 631, compared to the second embodiment of the presentinvention.

The current source 631 comprises a resistance R₃, one end of which isconnected to an output terminal of a gate controller 31, a NPN bipolartransistor Q₁, an emitter of which is connected to other end of theresistance R₃, a base of which is connected to a grounding voltageG_(ND), and a collector of which is connected to a gate of a powerPMOSFET transistor PM₁, and a P_(NP) bipolar transistor Q₂, an emitterof which is connected to the other end of the resistance R₃, a base ofwhich is connected to a grounding voltage G_(ND), and a collector ofwhich is connected to a gate of a power NMOSFET transistor NM₁.

More specifically, when one of the power MOSFET transistors PM₁ and NM₁is turned on, a capacitor connected to the turned-on power MOSFETtransistor PM₁ or NM₁ is charged or discharged through the resistance orzener diode, and then, if a switching frequency of the gate controller31 is slow, the turned-on power MOSFET transistor PM₁ or NM₁ is turnedoff. However, as shown in FIG. 6, if currents through the resistance andthe zener diode are compensated by the current source 631, the gatevoltage is maintained constant. At this time, only one of the two biportransistors Q₁ and Q₂, which is connected to the turned-on power MOSFETtransistor PM₁ or NM₁, is turned on and generates current and the otheris turned off. The current is determined by adjusting a value of R₃, andthe gate-source voltage of the turned-on power MOSFET transistor PM₁ orNM₁ is determined by multiplying the resistance R₁ or R₂ and thecurrent.

FIG. 7 is a drawing illustrating a circuit for driving a gate of a powerMOSFET in a digital audio amplifier, according to a fifth embodiment ofthe present invention.

Referring to FIG. 7, a circuit for driving a gate 73 further comprises acurrent source 731, compared to the third embodiment of the presentinvention. The current source 731 has the same structure with thecurrent source 631. The circuit for driving the gate 73, like thecircuit for driving the gate 63, prevents the power MOSFET transistorsPM₁ and NM₁ from being turned off by the current source 731 when thefrequency of the output signal of the gate controller 31 is slow.

In the current sources 631 and 731 of FIGS. 6 and 7, an NMOSFETtransistor may be used instead of the NPN polar transistor Q₁ and aPMOSFET transistor may also be used instead of the PNP bipolartransistor Q₂. In the case of the PMOSFET transistor, a source isconnected to the other end of the resistance R₃, a gate is connected toa grounding voltage V_(SS), and a drain is connected to the gate of thepower PMOSFET transistor PM₁. In the case of the NMOSFET transistor, asource is connected to the other end of the resistance R₃ and a gate isconnected to the grounding voltage V_(SS), and a drain is connected tothe gate of the power NMOSFET transistor NM₁.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the accompanying claims.

As described above, a circuit for driving a gate according to thepresent invention has an advantage in that the circuit safely andeffectively transmits an output signal of a gate controller irrespectiveof a frequency and duty-cycle of the output signal of, when transmittingthe output signal of the gate controller to the power MOSFET transistorusing a higher power source voltage than the gate controller. Therefore,the circuit is suitable for a case where the duty-cycle of the outputsignal of the gate controller dramatically changes and the frequency isirregular.

1. A circuit for driving a gate of a power metal-oxide semiconductorfield effect transistor (MOSFET) in a digital audio amplifier includinga power PMOSFET transistor in which a first power source voltage isapplied to a source and an output terminal is connected to a drain; apower NMOSFET transistor in which the output terminal is connected to adrain and a second power source voltage is applied to a source; a gatecontroller which uses a third power source voltage which is lower thanthe first power source voltage and a fourth power source voltage whichis lower than the second power source voltage, and controls gates of thepower PMOSFET and NMOSFET transistors; and an output filter which isconnected to the output terminal and has an inductor and a capacitor,the circuit comprising: a first resistance connected between the firstpower source voltage and the gate of the power PMOSFET transistor; asecond resistance connected between the second power source voltage andthe gate of the power NMOSFET transistor; a first capacitor connectedbetween an output terminal of the gate controller and the gate of thepower PMOSFET transistor; a second capacitor connected between theoutput terminal of the gate controller and the gate of the power NMOSFETtransistor; a first diode connected between the output terminal of thegate controller and the gate of the power PMOSFET transistor; and asecond diode connected between the output terminal of the gatecontroller and the gate of the power NMOSFET transistor.
 2. The circuitof claim 1, wherein the first and second diodes are zener diodes.
 3. Acircuit for driving a gate of a power MOSFET in a digital audioamplifier including a power PMOSFET transistor in which a first powersource voltage is applied to a source and an output terminal isconnected to a drain; a power NMOSFET transistor in which the outputterminal is connected to a drain and a second power source voltage isapplied to a source; a gate controller which uses a third power sourcevoltage which is lower than the first power source voltage and a fourthpower source voltage which is lower than the second power sourcevoltage, and controls gates of the power PMOSFET and NMOSFETtransistors; and an output filter which is connected to the outputterminal and has an inductor and a capacitor, the circuit comprising: afirst resistance connected between the first power source voltage andthe gate of the power PMOSFET transistor; a second resistance connectedbetween the second power source voltage and the gate of the powerNMOSFET transistor; a first capacitor connected between an outputterminal of the gate controller and the gate of the power PMOSFETtransistor; a second capacitor connected between the output terminal ofthe gate controller and the gate of the power NMOSFET transistor; afirst diode, one end of which is connected to the first power sourcevoltage; a second diode, one end of which is connected to the other endof the first diode and other end of which is connected to the gate ofthe power PMOSFET transistor; a third diode, one end of which isconnected to the second power source voltage; and a fourth diode, oneend of which is connected to the other end of the third diode and otherend of which is connected to the gate of the power NMOSFET transistor.4. A circuit for driving a gate of a power MOSFET in a digital audioamplifier including a power PMOSFET transistor in which a first powersource voltage is applied to a source and an output terminal isconnected to a drain; a power NMOSFET transistor in which the outputterminal is connected to a drain and a second power source voltage isapplied to a source; a gate controller which uses a third power sourcevoltage which is lower than the first power source voltage and a fourthpower source voltage which is lower than the second power sourcevoltage, and controls gates of the power PMOSFET and NMOSFETtransistors; and an output filter which is connected to the outputterminal and has an inductor and a capacitor, the circuit comprising: afirst resistance connected between the first power source voltage andthe gate of the power PMOSFET transistor; a second resistance connectedbetween the second power source voltage and the gate of the powerNMOSFET transistor; a first capacitor, one end of which is connected anoutput terminal of the gate controller; a second capacitor, one end ofwhich is connected to the output terminal of the gate controller; afirst diode, one end of which is connected to the first power sourcevoltage and other end of which is connected to the gate of the powerPMOSFET transistor; a second diode, one end of which is connected to theother end of the first capacitor and other end of which is connected tothe gate of the power PMOSFET transistor; a third diode, one end ofwhich is connected to the second power source voltage and other end ofwhich is connected to the gate of the power NMOSFET transistor; and afourth diode, one end of which is connected to the other end of thesecond capacitor and other end of which is connected to the gate of thepower NMOSFET transistor.
 5. The circuit of claim 3 or 4, wherein thefirst through fourth diodes are zener diodes.
 6. The circuit of claim 3or 4 further comprising a current source which is connected to the gatesof the power PMOSFET and NMOSFET transistors and the output terminal ofthe gate controller.
 7. The circuit of claim 6, wherein the currentsource comprises: a resistance, one end of which is connected to theoutput terminal of the gate controller; a NPN bipolar transistor, anemitter of which is connected to other end of the resistance, a base ofwhich is connected to a grounding voltage, and a collector of which isconnected to the gate of the power PMOSFET transistor; and a PNP bipolartransistor, an emitter of which is connected to the other end of theresistance, a base of which is connected to a grounding voltage, and acollector of which is connected to the gate of the power NMOSFETtransistor.
 8. The circuit of claim 6, wherein the current sourcecomprises: a resistance, one end of which is connected to the outputterminal of the gate controller; a NMOSFET transistor, a source of whichis connected to other end of the resistance, a gate of which isconnected to a grounding voltage, and a drain of which is connected tothe gate of the power PMOSFET transistor; and a PMOSFET transistor, asource of which is connected to the other end of the resistance, and agate of which is connected to a grounding voltage, and a drain of whichis connected to the gate of the power NMOSFET transistor.